I understand the emotional desire to “keep the collection together”, but doing so would be a major mistake if the goal is to achieve the maximum return on the sale.
By selling such a large collection as a single lot, you are eliminating 99% of the possible buyers. Very few collectors will have the cash and the desire to buy a whole collection and if they do, it will only be to break up the collection by cherry picking the pieces they want and then reselling what they don’t as single pieces.
Like any other type of collecting, the danger is that a significant portion of the value of the collection could lie in just a few of the decoys. By selling them as one lot, you’re risking giving those pieces away at a fraction of their true value because the collector that REALLY would pay big money can’t/won’t buy the entire collection just for one piece.
My advice would be to take your time, get 2 or more professional evaluations, and get additional opinions about how to achieve the best sale price. Such a collection could well be worth listing at a specialty sporting auction to attract the specialized buyer.
Grouse